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Code Quiz: Box Length Requirement

Nov. 21, 2024

Test your knowledge of the NEC with this challenging question.

Based on the 2023 NEC.

Question: The length of the box shall not be less than ________ the outside diameter, over sheath, of the largest shielded or lead-covered conductor or cable entering the box.

See answer below.

Answer: 48 times.

Explanation: The answer to this question is found in Sec. 314.71(A) of the NEC. It states, "The length of the box shall not be less than 48 times the outside diameter, over sheath, of the largest shielded or lead-covered conductor or cable entering the box."

Lupacchino is a senior design engineer with Gaylor Electric, Inc. in Noblesville, Ind. and serves as an alternate on NEC Code-Making Panel No. 3. He is currently licensed in more than 80 jurisdictions. He can be reached at [email protected]

About the Author

John Lupacchino | Senior Design Engineer

John began his career in electrical construction as an apprentice and worked his way through the trade. He is currently licensed in more than 80 jurisdictions. With more than 35 years of experience, he now plays a vital role in Gaylor Electric’s Engineering Department, where he serves as a senior design engineer. With a focus on design engineering, quality assurance, and code compliance, he has earned the highest level of respect from industry professionals alike. John currently serves as an alternate on NFPA 70 Code Making Panel No. 3. In addition, he enjoys sharing his electrical knowledge through education. As an Associated Builders and Contractors instructor, he continues to help grow a new generation of high-performing construction leaders.